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| United States Patent |
6,022,589
|
|
Klosowski
, et al.
|
February 8, 2000
|
Conservation of organic and inorganic materials
Abstract
The use of certain siloxane and silane materials for the conservation of
organic and inorganic materials. More specifically, this invention deals
with a method of impregnating organic and inorganic materials with
siloxanes and silanes and ultimately curing such materials to provide
preservation properties to such materials. An especially significant use
of the method is to preserve and conserve ancient artifacts. The curable
materials are represented by silanol containing polymers crosslinked with
trialkoxysilanes.
| Inventors:
|
Klosowski; Jerome Melvin (Bay City, MI);
Smith; Charles Wayne (Bryan, TX);
Hamilton; Donny Leon (Bryan, TX)
|
| Assignee:
|
Dow Corning Corporation (Midland, MI)
|
| Appl. No.:
|
129296 |
| Filed:
|
August 5, 1998 |
| Current U.S. Class: |
427/297; 427/340; 427/350; 427/351; 427/387; 427/389; 427/389.7; 427/393; 427/393.6; 427/408; 427/411; 427/412 |
| Intern'l Class: |
B05D 001/36 |
| Field of Search: |
427/387,297,393,340,350,351,389,389.7,389.9,393.6,407.2,408,411,412
|
References Cited
U.S. Patent Documents
| 5205860 | Apr., 1993 | Narula et al. | 106/2.
|
| 5695551 | Dec., 1997 | Buckingham et al. | 106/2.
|
| Foreign Patent Documents |
| 4-012806 | Jan., 1992 | JP.
| |
Primary Examiner: Cameron; Erma
Attorney, Agent or Firm: McKellar; Robert L.
Parent Case Text
This application is a continuation-in-part of U.S. application Ser. No.
08/780,508, filed Jan. 8, 1997 and now abandoned.
Claims
What is claimed is:
1. A method of conserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a curable polymeric system comprising (i) a siloxane polymer or a
mixture of siloxane polymers having an average of at least two silanol
groups per molecule and (ii) sufficient crosslinker or a mixture of
crosslinkers to crosslink a significant portion of the siloxane polymer or
mixture of siloxane polymers (i), and thereafter,
(II) exposing the product of (I) to a catalyst or a mixture of catalysts
for a time sufficient to initiate curing of the product of (I), wherein
the crosslinkers are selected from the group consisting of hydrolyzable
silanes selected from the group having the formulae
1. RSi(OR').sub.3,
2. RSi(OX).sub.3,
3. RSi(OCOR').sub.3
4. RSi(oCOR').sub.n (OR').sub.3-n, wherein n has a value of 1 or 2 or,
5. mixtures of 1 to 4;
wherein R in each case is selected from the phenyl group, hydrogen, vinyl,
or an alkyl group having from 1 to 12 carbon atoms, R' in each case is
selected from hydrogen, vinyl, or an alkyl group having from 1 to 8 carbon
atoms, and OX is an oximo group.
2. A method of conserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a curable polymeric system comprising (i) a siloxane polymer or a
mixture of siloxane polymers having an average of at least two silanol
groups per molecule and (ii) sufficient crosslinker or a mixture of
crosslinkers to crosslink the siloxane polymer or mixture of siloxane
polymers (i), and thereafter,
(II) exposing the product of (I) to a catalyst or a mixture of catalysts
for a time sufficient to cure the product of (I), wherein the crosslinkers
are selected from the group consisting of hydrolyzable silanes selected
from the group consisting of
1. RSi(OR').sub.3
2. RSi(OX).sub.3
3. RSi(OCOR').sub.3
4. RSi(OCOR').sub.n (OR').sub.3-n wherein n has a value of 1 or 2 or
5. mixtures of 1 to 4;
wherein R in each case is selected from the phenyl group, hydrogen, vinyl,
or an alkyl group having from 1 to 12 carbon atoms, R' in each case is
selected from hydrogen, vinyl, or an alkyl group having from 1 to 8 carbon
atoms, and OX is an oximo group.
3. The method as claimed in claim 2 wherein the hydrolyzable silane is
isobutyltrimethoxysilane.
4. A method as claimed in claim 2 wherein the hydrolyzable silane is an
oximosilane.
5. A method as claimed in claim 4 wherein the oximosilane is
methyltrioximosilane.
6. A method as claimed in claim 2 wherein the hydrolyzable silane is an
acetoxysilane.
7. A method as claimed in claim 6 wherein the acetoxysilane is
methyltriacetoxysilane.
8. A method as claimed in claim 2 wherein there is more than one
crosslinker.
9. A method as claimed in claim 8 wherein there is two crosslinkers and
they are both acetoxysilanes.
10. A method as claimed in claim 9 wherein the acetoxysilanes are
methylacetoxysilane and ethylacetoxysilane and they are present in a
weight ratio of about 50:50.
11. A method as claimed in claim 2 wherein the impregnation is assisted by
negative pressure.
12. A method as claimed in claim 2 wherein the impregnation is assisted by
positive pressure.
13. A method as claimed in claim 2, wherein the material selected for (I)
is an organic material.
14. A method as claimed in claim 13, wherein the organic material is
leather.
15. A method as claimed in claim 13, wherein the organic material is wood.
16. A method as claimed in claim 13, wherein the organic material is human
body tissue.
17. A method as claimed in claim 13, wherein the organic material is
non-human body tissue.
18. A method as claimed in claim 13, wherein the organic material is plant
material.
19. A method as claimed in claim 13, wherein the organic material is bone.
20. A method as claimed in claim 13, wherein the organic material is paper.
21. A method as claimed in claim 14, wherein the paper is a photograph.
22. A method as claimed in claim 2, wherein the material selected for (I)
is an inorganic material.
23. A method as claimed in claim 22, wherein the inorganic material is
glass.
24. A method as claimed in claim 22, wherein the inorganic material is
ceramic.
25. A method as claimed in claim 22, wherein the inorganic material is
pottery.
26. A product when prepared by the method of claim 2.
27. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a crosslinker or a mixture of crosslinkers sufficient to crosslink a
significant portion of a siloxane polymer or a mixture of siloxane
polymers having an average of at least two silanol groups per molecule;
(II) thereafter, impregnating the product of (I) with siloxane polymer or a
mixture of siloxane polymers having an average of at least two silanol
groups per molecule;
(III) thereafter, exposing the product of (II) to a catalyst or a mixture
of catalysts for a time sufficient to initiate curing of the product of
(II).
28. A product when prepared by the method of claim 27.
29. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a crosslinker or a mixture of crosslinkers sufficient to crosslink a
significant portion of a siloxane polymer or a mixture of siloxane
polymers having an average of at least two silanol groups per molecule;
(II) thereafter, impregnating the product of (I) with a siloxane polymer or
a mixture of siloxane polymers having an average of at least two silanol
groups per molecule;
(III) thereafter, exposing the product of (II) to a catalyst or a mixture
of catalysts for a time sufficient to initiate curing of the product of
(II) , and thereafter,
(IV) curing the product of (II).
30. A method as claimed in claim 29 wherein the impregnation in (I) is
assisted by negative pressure.
31. A method as claimed in claim 29 wherein the impregnation in (I) is
assisted by positive pressure.
32. A method as claimed in claim 29 wherein the impregnation in (II) is
assisted by negative pressure.
33. A method as claimed in claim 29 wherein the impregnation in (ii) is
assisted by positive pressure.
34. A method as claimed in claim 29 wherein both the impregnation in (I)
and (II) are assisted by negative pressure.
35. A product when prepared by the method of claim 29.
36. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule;
(II) thereafter, impregnating the product of (I) with a crosslinker or a
mixture of crosslinkers sufficient to crosslink a significant portion of
the siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule;
(III) thereafter, exposing the product of (II) to a catalyst or a mixture
of catalysts for a time sufficient to initiate curing of the product of
(II).
37. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule;
(II) thereafter, impregnating the product of (I) with a crosslinker or a
mixture of crosslinkers sufficient to crosslink a significant portion of
the siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule;
(III) thereafter, exposing the product of (II) to a catalyst or a mixture
of catalysts for a time sufficient to initiate curing of the product of
(II), and thereafter,
(IV) curing the product of (II).
38. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a cyclosiloxane or a mixture of cyclosiloxanes having an average of at
least two silane hydrogens per molecule and thereafter,
(II) exposing the product of (II) to a catalyst or a mixture of catalysts
for a time sufficient to initiate curing of the product of (II).
39. A product when prepared by the method of claim 38.
40. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a non-cyclic siloxane or a mixture of non-cyclic siloxanes having an
average of at least two silane hydrogens per molecule and having a
molecular weight of 10,000 g/mole or less, and thereafter,
(II) exposing the product of (II) to a catalyst or a mixture of catalysts
for a time sufficient to initiate curing of the product of (II).
41. A method as claimed in claim 40 wherein there is additionally present
cyclic siloxanes or a mixture of cyclic siloxanes having an average of at
least two silane hydrogens per molecule.
42. A method as claimed in claim 41 in which the cyclosiloxane is a cyclic
trimer siloxane.
43. A method as claimed in claim 41 in which the cyclosiloxane is a cyclic
tetramer siloxane.
44. A method as claimed in claim 41 in which the cyclosiloxane is a cyclic
pentamer siloxane.
45. A method as claimed in claim 41 in which the cyclosiloxane is a mixture
of cyclosiloxanes.
46. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule and thereafter,
(II) exposing the product of (I) to a catalyst or a mixture of catalysts
for a time sufficient to initiate curing of the product of (I).
47. A method of preserving organic and inorganic materials, the method
comprising:
(I) Impregnating a material selected from
a. organic materials or
b. inorganic materials
with a hydrolyzable silane or a mixture of hydrolyzable silanes and
thereafter,
(II) exposing the product of (I) to a catalyst or a mixture of catalysts
for a time sufficient to initiate curing of the product of (I).
48. A method as claimed in claim 47 wherein the hydrolyzable silane is
tetraethylorthosilicate.
49. A method as claimed in claim 48 wherein there is additionally present
an alkoxysilane or a mixture of alkoxysilanes having the general formula:
R.sub.a Si(OR').sub.4-a
wherein R is selected from the phenyl group, hydrogen, vinyl, or an alkyl
group having from 1 to 12 carbon atoms, R' is selected from hydrogen,
vinyl, or an alkyl group having from 1 to 6 carbon atoms and, a has a
value of 1 or 2.
50. A method as claimed in claim 49 wherein the hydrolyzable silane is
isobutyltrimethoxysilane.
Description
This invention relates to the use of certain siloxane and silane materials
for the conservation of organic and inorganic materials. More
specifically, this invention deals with a method of impregnating organic
and inorganic materials with siloxanes and silanes and ultimately curing
such materials to provide preservation properties to such materials. An
especially significant use of the method is to preserve and conserve
ancient artifacts.
Plastination and/or conservation are terms that are often used in this art
to denote the preservation of perishable biological specimens, especially
soft, putrifiable materials with high water content. During the
plastination method, water, and part or all of the fat (if present), are
replaced by a curable resin system or elastomer system in order to
optimize the preservation of the materials and to optimize the natural
appearance of the material or enhance its aesthetic appearance.
Plastination is utilized therefore, in the preservation of whole body
organs and bones, both animal and human, for pathological and anatomical
studies; in zoology for the plastination of small animals, such as
beetles, spiders, frogs, and reptiles, such as turtles, salamanders; in
botany, for fungus and higher plant specimens; archeology for the
preservation of wood, ceramics, pottery, glass, leather, jewelry, and the
like.
Preservation techniques have also been used in the treating of books,
newspapers, photographs and materials of a like nature.
BACKGROUND OF THE INVENTION
Plastination utilizes many different curable materials, for example,
polyepoxides, polyesters, silicone rubbers, and the like. The inventors
herein are aware of several patents which show the use of certain
materials for plastination processes.
For example, U.S. Pat. No. 2 106 261, which issued Jan. 25, 1938 to
Weidemann deals with a process in which the specimen which is to be
treated is immersed in bleach. The specimen is then washed with water to
remove essentially all of the bleach and the specimen is set in a
dehydrating solution of alcohols, acetone or combinations thereof.
Finally, the specimen is dried and coated with a clear lacquer to
impregnate or encapsulate the specimen. There is no clear definition of
the make up of the clear lacquer.
U.S. Pat. No. 4 205 059 which issued on May 27, 1980 to Von Hagens uses a
more elaborate process in which the process starts out with the
replacement of the water content of the specimen, in this case, animal or
vegetable tissue, with an organic solvent which is volatile in a vacuum
and at ambient temperature. Then, the specimen, which contains solvent, is
held in contact with a fluid precursor polymer system in a vacuum and at a
specified temperature until the solvent is volatilized and replaced in the
specimen by the polymeric system. The curable system is stated as being
capable of being polymerized into a solid, water insoluble, synthetic
resin. The specimen to then subjected to a "drying down" time in which the
excess polymeric system is allowed to flow by gravity from the specimen.
The specimen is then held under polymerization conditions until the resin
is cured. Claim 6 of that reference discloses that the resin is "a
silicone rubber". The curable silicone rubber was described as a fully
compounded curable material.
U.S. Pat. No. 2,244,992 which issued Jan. 13, 1981 to Von Hagens is a
divisional of the aforementioned U.S. patent and therefore does not need
additional discussion herein.
U.S. Pat. No. 4,278,701 which issued Jul. 14, 1981 to van Hagens,
disclaimed the '059 patent, and the subject matter therein is the same as
the '059 patent except that it does not disclose the "ambient temperature"
limitation of the '059 patent.
U.S. Pat. No. 4 320 157 which issued Mar. 16, 1982 is directed to a method
of converting cut sections of bio tissue into examinable plastinated sheet
by a method which includes pre-treating to render the specimen suitable
for impregnation, thereafter, impregnating with a fluid precursor,
compressing the specimen between two parallel panels, filling the
resulting formation with impregnating fluid, curing the fluid and removing
the plates.
THE INVENTION
This invention deals with new and novel methods of conserving and
preserving organic and inorganic materials through the use of novel
processes not heretofore found in the prior art.
With more specificity, this invention deals in one embodiment with a method
of conserving organic and inorganic materials, wherein the method
comprises (I) impregnating a material selected from (a.) organic materials
and (b.) inorganic materials with a curable polymeric system comprising
(i) a siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule and (ii) sufficient
crosslinker or a mixture of crosslinkers to crosslink a significant
portion of the siloxane polymer or mixture of siloxane polymers (i), and
thereafter, (II) exposing the product of (I) to a catalyst or a mixture of
catalysts for a time sufficient to initiate the cure of the product of
(I), wherein the crosslinkers are selected from the group consisting of
hydrolyzable silanes having the formula RSi(OR').sub.3 wherein R is
selected from the phenyl group, hydrogen, vinyl, or an alkyl group having
from 1 to 12 carbon atoms and R' is selected from hydrogen, vinyl, or an
alkyl group having from 1 to 8 carbon atoms.
Yet another embodiment is a method in which the product of (II) is
subjected to a treatment to cure the curable system formed by the siloxane
polymer and the crosslinker of this method.
Still further, another embodiment of this invention is a method of
preserving organic and inorganic materials, the method comprising a step
(I) in which a material selected from (a.) organic materials and (b.)
inorganic materials, is impregnated with a crosslinker or a mixture of
crosslinkers sufficient to crosslink a significant portion of a siloxane
polymer or a mixture of siloxane polymers having an average of at least
two silanol groups per molecule; (II) thereafter, impregnating the product
of (I) with siloxane polymer or a mixture of siloxane polymers having an
average of at least two silanol groups per molecule, and (III) thereafter,
exposing the product of (II) to a catalyst or a mixture of catalysts for a
time sufficient to initiate curing of the product of (II).
As in the first embodiment, this process can be extended to include a step
to cure the product of (II).
Another embodiment of this invention is a method of preserving organic and
inorganic materials, wherein the method comprises (I) impregnating a
material selected from (a.) organic is materials and (b.) inorganic
materials with a siloxane polymer or a mixture of siloxane polymers having
an average of at least two silanol groups per molecule and (II)
thereafter, impregnating the product of (I) with a crosslinker or a
mixture of crosslinkers sufficient to crosslink a significant portion of
the siloxane polymer or a mixture of siloxane polymers having an average
of at least two silanol groups per molecule. Thereafter, (III), exposing
the product of (II) to a catalyst or a mixture of catalysts for a time
sufficient to initiate curing of the product of (II).
As before, an additional step can be used which subjects the specimen, that
is treated by this method, to a curing step.
Turning to another embodiment of this invention, it has been discovered
that the method embodied in the first embodiment can be modified to a
method of preserving organic and inorganic materials, wherein the method
comprises (I) impregnating a material selected from organic materials and
inorganic materials with a cyclosiloxane or a mixture of cyclosiloxanes
having an average of at least two silane hydrogens per molecule and
thereafter, exposing the product created thereby to a catalyst or a
mixture of catalysts for a time sufficient to initiate curing of the
product. As before, an additional step can be used which subjects the
specimen, that is treated by this method, to a curing step.
Still further, an embodiment of this invention is the substitution of
essentially linear methylhydrogen siloxanes for the cyclic siloxanes of
the method just supra and such a method preserves organic and inorganic
materials using a non-cyclic siloxane or a mixture of non-cyclic siloxanes
having an average of at least two silane hydrogens per molecule and having
a molecular weight of 5000 g/mole or less, and thereafter, exposing the
product obtained thereby to a catalyst or a mixture of catalysts for a
time sufficient to initiate curing of the product. Once again, it should
be apparent to those skilled in the art upon a close reading of this
specification that a further step of curing the product can be utilized in
this method.
A further embodiment of this invention is a method of preserving organic
and inorganic materials wherein the method comprises impregnating a
material selected from organic materials and inorganic materials with a
siloxane polymer or a mixture of siloxane polymers having an average of at
least two silanol groups per molecule and thereafter, exposing the product
obtained thereby to a catalyst or a mixture of catalysts for a time
sufficient to initiate curing of the product of (I) and if desired,
completing the method with a curing step.
There is also a unique method embodied within this invention which is a
method of preserving organic and inorganic materials, in which the method
comprises impregnating a material selected from organic materials and
inorganic materials with a hydrolyzable silane or a mixture of
hydrolyzable silanes and thereafter, exposing the product obtained thereby
to a catalyst or a mixture of catalysts for a time sufficient to initiate
curing of the product and then, if desired, completing the method by
curing the product. Preferred for this unique method is the crosslinker
tetraethylorthosilicate. Further, this method can be additionally modified
by the use of alkoxysilanes in conjunction with the orthosilicate, which
alkoxy silanes, or mixtures of alkoxysilanes have the general formula
R.sub.a Si(OR').sub.4-a wherein R is selected from the phenyl group,
hydrogen, vinyl, or an alkyl group having from 1 to 12 carbon atoms, R' is
selected from hydrogen, vinyl, or an alkyl group having from 1 to 8 carbon
atoms and, a has a value of 1 or 2.
A further embodiment of the use of hydrolyzable silanes is a curable
polymeric system comprising (i) a siloxane polymer or a mixture of
siloxane polymers having an average of at least two silanol groups per
molecule and (ii) sufficient crosslinker to crosslink a significant
portion of the siloxane polymer or mixture of siloxane polymers (i), and
thereafter, curing the product of (I) , wherein the crosslinker is
selected from a group consisting of R"Si(Oxime).sub.3 and
R"Si(Oxime).sub.4 wherein R" is selected from the phenyl group, hydrogen,
vinyl, or an alkyl group having from 1 to 12 carbon atoms.
Yet another embodiment of this invention is a method of preserving organic
and inorganic materials, in which the method comprises impregnating a
material selected from organic materials and inorganic materials with (i)
a siloxane polymer or a mixture of siloxane polymers having an average of
at least two unsaturated groups per molecule; (ii) sufficient crosslinker
or a mixture of crosslinkers to crosslink a significant portion of the
siloxane polymer or mixture of siloxane polymers (i) wherein the
crosslinker or crosslinkers are comprised of organosilicon compounds
having at least two hydrogen atoms per silicon and are selected from the
group consisting of (a) silanes, (b) siloxanes and (c) mixtures of (a) and
(b) and, (iii) a platinum catalyst, and thereafter, (II) allowing the
product of (I) to cure.
Finally, there is disclosed a method of configuring wood products, which
method comprises (I) impregnating the wood product with a curable system
and thereafter (II) configuring the wood product to a desired shape and
(III), while maintaining the wood product in the configuration of (II),
curing the curable system.
With respect to the inventive method herein, the term "negative pressure"
means without pressure and essentially in a vacuum, while the term
"positive pressure" denotes the absence of a vacuum. The examples herein
describe negative pressure in inches of mercury and generally, 3 to 5
inches is a poor vacuum and thirty inches is considered to be a good
vacuum.
The substrates utilized in the method of this invention are first subjected
to a dehydration step in which any water in the substrate is displaced, or
is essentially displaced by a solvent or the like.
The general method used herein was a modified method of the method used by
those skilled in the art. In general, samples were first dehydrated in
acetone which was contained in a freezer mounted vacuum chamber
(hereinafter "FMVC"). After dehydration, the samples were placed into the
materials for impregnation, such materials being set forth in detail in
the following examples. Each of the samples was treated by the
impregnating material for a period of several hours as noted in the
examples. The process can be found in detail with regard to Example 1
below.
The siloxanes used in these examples are the following unless otherwise
noted in the example:
Siloxane 1=a siloxane having an average of two vinyl groups per molecule,
essentially on the terminal ends of the molecule and having dimethylsiloxy
units, said dimethylsiloxy units having a degree of polymerization of
about 100.
Siloxane 2=a siloxane having an average of two hydroxy groups (silanol
groups) per molecule, essentially on the terminal ends of the molecule and
having dimethylsiloxy units, said dimethylsiloxy units having a degree of
polymerization of about 100.
Siloxane 3=a hydroxy terminated siloxane as in Siloxane 2 except its degree
of polymerization is about 3 to 5.
Siloxane 4=a hydroxy terminated siloxane as in Siloxane 2 except its degree
of polymerization is about 35 to 40.
Siloxane 5=a hydroxy terminated siloxane as in Siloxane 2 except its degree
of polymerization is about 6 to 10.
Siloxane 6=a hydroxy terminated siloxane as in Siloxane 2 except its degree
of polymerization is about 300.
EXAMPLE 1
Preservation Of Artifacts: Corn Cobs
A large corn cob specimen recovered from the 1870 provenance of excavations
at the Yorktown, Pa. site was selected for this experiment.
Prior to treatment, the cob was stored in a glass jar in a mixture of
alcohol and water to prevent crumbling during handling. The core area of
the cob was completely hollow and although there was a great deal of
debris and exfoliation in the alcohol/water solution, the cob was soft to
the touch and did not crumble when handled.
The cob was removed from the alcohol/water solution and rinsed for one hour
in a free-running gentle bath of fresh water as a means of removing
sediment and debris from the surfaces of the cob. The cob was then placed
on paper towels and allowed to drain of excess surface water for two
minutes before it was weighed and measured. In addition to weighing the
cob, measurements of the cob were recorded for the longest points along
the length of the sample as well as the mid-section diameter point of the
cob. The wet weight of the cob was 16.8 grams and the sample measured 5.6
centimeters in length and 2.63 centimeters in width.
Before treatment, the cob was placed in an initial bath of acetone, which
had been stored at the same temperature as the solution in which the cob
had been stored, to prevent additional stress on the sample. The beaker
containing the acetone and cob was then placed in a freezer mounted vacuum
chamber and for six hours, a vacuum of 26.5 Psi was applied. The cessation
of rapid bubbling indicated that the cob had lost essentially all of the
water originally present therein. At this point, the acetone was replaced
with fresh acetone that had also been stored in the freezer. The cob was
allowed to sit in this solution in the freezer for twelve hours prior to
impregnation.
After allowing free-running acetone to drain from the sample for less than
one minute, the cob was placed in a clean, dry beaker and freezer cold
polydimethylsiloxane fluid having hydroxyl groups on each end of the
molecule and having a molecular weight of 350 g/mole was added to the
beaker to submerge the cob thereunder. The cob was slightly buoyant in
nature and therefore, the cob was arrested beneath the surface of the
silicone fluid using a fine mesh wire screen. With the screen in place,
the beaker was placed in the freezer mounted vacuum chamber and a vacuum
of 26.5 Torr was applied for eight hours and then the cob was allowed to
sit in the silicone fluid in the freezer for twelve hours without any
additional vacuum being applied.
Thereafter, the silicone fluid was carefully decanted from the beaker and
the cob was removed and allowed to drain to remove excess liquid for about
two minutes. The cob was then placed in a clean beaker and
ethyltrimethoxysilane as a crosslinker was added in an amount to submerge
the cob. The beaker was then returned to the freezer mounted vacuum
chamber and as before, a vacuum of 26.5 Torr was applied. Very few bubbles
were noted and after eight hours, the application of a vacuum was
discontinued and the cob was allowed to sit in solution in the freezer for
an additional twelve hours.
A heated oven containing a chamber was used to heat the sample to
130.degree. F. The heated oven consisted of the oven, containing a chamber
inside wherein the chamber was essentially a polypropylene pail with a
tight fitting lid which was inverted in the oven and laid on the bottom
surface of the oven. On the inside surface of the lid of the pail was
placed a small petri dish and the petri dish was surmounted by a wire
support screen onto which was placed the cob. The petri dish was used to
contain the desired catalyst for the curing step of the process.
Two ounces of Fastcat 2003 catalyst was placed in the petri dish and the
cob was subjected to the 130.degree. temperature for a period of eight
hours, at which time the cob was removed from the chamber and examined.
The surfaces of the cob were slightly wet to the human touch. The catalyst
was removed from the petri dish and two ounces of fresh catalyst was added
to the dish. The cob was then placed in the chamber and subjected to an
additional twenty-four hours at 130.degree. and after checking the cob for
cure, for an additional three days of treatment. At this point, pipe
cleaners were saturated with the catalyst and the pipe cleaners were
inserted into the core of the cob and the outside of the cob was treated
by sprinkling the catalyst on a lint free rag, and wrapping the cob in the
cloth whereupon the cob was allowed to sit in this fashion at room
temperature for two days and then the cob was evaluated.
Comparisons were made between the cob treated by the process of this
invention and several other cobs that had been air-dried from water-logged
samples from the same provenance and time period. The initial observations
indicated that extensive shrinkage and distortion destroyed the aesthetics
of the cobs which were allowed to air-dry.
Very little particulate was noted in either the silicone liquid or the
ethytrimethoxysilane after they were decanted following the treatment by
each material. Post treatment measurements and weighing of the cob
indicated that the process was very successful in preserving the original
waterlogged artifact. The cob weighed 16.6 grams and measured 5.6
centimeters in length and 2.5 centimeters in diameter, by measuring the
same point on the cob from which the original measurements had been taken.
The cob thus changed in weight by -1.2% and only diminished by -5.2% in
diameter. The post treatment length of the cob remained the same as the
wet length of the cob when first measured. A comparison can be made by
reference to TABLE I, below.
The cob is darker in color than the coloration of most of the corn cobs, no
attempts were made at removing stains and discoloration which may have
been caused by the long time close association of the artifact to
sediments and other decomposing materials.
TABLE I
______________________________________
SAMPLE WEIGHT/GRAMS LENGTH/Cm WIDTH/Cm
______________________________________
Original wet
16.80 5.60 2.63
dimensions
Post treatment
16.60 5.60
2.50
dimensions
Percentage
-1.2048% 0.0% 5.20%
Change
______________________________________
EXAMPLE 2
Preservation Of Artifacts: Cork
Six waterlogged corks from the 1692 provenance of excavations at Port
Royal, Jamaica were used in this experiment. Three different siloxane
liquids were used in this experiment, namely polydimethylsiloxanes having
hydroxy groups on each end of the molecule and having molecular weights of
A=9000, B=2700, and C=550 g/mole, respectively. Before treatment, all six
corks had been stored in a polyethylene bag in fresh tap water and all of
the corks were removed from the bag and placed in a large vat and rinsed
with running water for two days. All of the corks were photographed, and
their configurations were drawn on paper for later comparison. All of the
corks were weighed and their dimensions measured and the same was
recorded. This information is found in TABLE IIA.
TABLE IIA
______________________________________
SPECI-
WET
MEN WEIGHT/gms.
LENGTH/cm. WIDTH/cm.
TREATMENT
______________________________________
1 10.5 3.60 2.13 air-dry
2 6.7
2.83
1.73
Siloxane A
3 2.84
1.95
Siloxane B
4 2.86.0
1.66
Siloxane B
5 6.5
3.09
1.73
Siloxane A
6 4.0
2.64
1.62
Siloxane C
______________________________________
One cork was left to air dry and was labeled specimen 1. The remainder of
the corks were placed in a bath of acetone to dehydrate them. The beaker
containing the acetone and corks was placed in a freezer mounted vacuum
chamber and a vacuum of minus 26.5 Torr was applied for eight hours. The
acetone was decanted and fresh acetone was added to the corks and this was
stored in the freezer for 12 hours.
Separate beakers were filled each with Siloxane A, Siloxane B, and Siloxane
C and the corks immersed therein and they were weighted to keep them
submerged. A vacuum of 26.5 Torr was applied to all of the samples for
five hours and the samples were allowed to sit with the vacuum off for
twelve hours in the freezer. Then, all of the corks were removed and
placed in a cotton bag and the bag containing the corks was immersed in
methylhydrogencyclosiloxane as a crosslinker. A vacuum of 26.5 Torr was
applies for one hour and then the corks were removed and placed
individually in an oven at 135.degree. F. which contained a tray of
Fastcat 2003 catalyst. They were held for two days and then they were
allowed to stand for 24 hours. The corks were then remeasured and
reweighed and the results can be found on TABLE IIB.
TABLE IIB
______________________________________
SAM- LENGTH
PLE WEIGHT CHANGE/%
CHANGE/%
WIDTH CHANGE/%
______________________________________
1 - 90.6 -27.8 -15.5
2 -55.2
00.0
3 -43.3
-5.1
4 -21.0
-3.6
5 -69.2
00.0
6 -10.5
______________________________________
EXAMPLE 3
In order to determine if the curable siloxane systems would in wooden
artifacts, experiments were carried out on fresh to determine the effects
of the system.
Thus, six samples of finely ground sawdust were prepared by mixing the 2
grams of the sawdust with 6.6 grams of the polymer of example 4. These
samples were labeled as 1A, 1B, 1C, 1D, 1E, and 1F. Nine additional
samples, each containing an additional 3 weight percent of
methyltrimethoxysilane were also prepared and these were labeled 2A, 2B,
2C, 2D, 2E, 2F, 3B, 3D, and 3F.
Sample numbers, catalyst types, chamber types and results can be found on
TABLE III.
TABLE III
______________________________________
SAMPLE #
CATALYST CHAMBER RESULT
______________________________________
1A Tin Octoate O 1
1B " 1+C
1C DBTDA
1+
1D C 2
1E TPT
1+
1F C 5
2A Tin Octaate
O 1+
2B C 2
2C DBTDA
O 1+
2D C 5
2E TPT
1+
2F C 5
3B Tin Octoate
Glass/C
1+
3D DBTDA
" 1+
3F TPT
"
______________________________________
2
TABLE III KEY
The results of 1 to 5 have the same meaning as in TABLE 5.
Six waterlogged tongue depressors that had been in contact with water for
about 10 years, were dehydrated in acetone in a freezer mounted vacuum
chamber and then placed in a solution of siloxane fluid mixed with about 3
weight percent methytrimethoxysilane. The impregnation was conducted for
about 24 hours and then the samples were placed in a glass containment
chamber for catalyst treatment using dibutyltindiacetate.
When finished, microscopy of thin cross sections of the finished samples
indicated that these samples had been successfully bulked (conserved) with
the curable siloxane system. Tongue depressors that had not been treated
as above, but were allowed to air dry, were warped and underwent extensive
shrinkage when dried. The treated tongue depressors retained the same
features as the untreated control tongue depressors, that is tongue
depressors that were not waterlogged, and the siloxane treated tongue
depressors were generally slightly darker in color than untreated control
tongue depressor samples.
EXAMPLE 4
Experiments were carried out on leather to determine if leather would
assume the impregnation to the extent that the process would be valuable
for impregnating artifactual leather.
Six samples of fresh untreated (i.e. non-tanned) cow hide were dehydrated
in the freezer mounted vacuum chamber using acetone. Three samples were
then subjected to a curable siloxane system consisting of siloxane 2,
combined with about three weight percent of methyltrimethoxysilane. One
each of the three samples was subjected, respectively, to
dibutyltindiacetate, tin Octoate, and tetraisopropyltitanate in closed,
individual chambers and one each of the three additional samples were
placed in open containment chambers with each of the three catalysts.
It was noted that the samples treated in the open ended containment
chambers were considerably harder than their counterparts treated in the
closed containment chambers. The samples treated in the closed containment
chambers remained more supple. All samples were essentially wholly
impregnated.
A second set of pieces of semi-finished hides were dehydrated in acetone at
room temperature for 18 hours at 28 inches of vacuum. The samples were
then placed into fresh acetone in a 4 liter stainless steel beaker, and
with a vacuum plate attached to the top of the beaker, the entire unit was
placed in a freezer for 4 hours of FMVC treatment at 9.5 inches of vacuum.
All of the sections were cut into approximately equal sizes measuring 1.5
inches by 1.75 inches in measurement. After dehydration, two pieces of
hide were placed directly in a 500 milliliter solution of siloxane 2 with
3 weight % MTM added. After placing a small piece of aluminum mesh over
the samples to prevent them from floating while processing, the samples
were placed into a 4 liter stainless steel beaker. A vacuum plate was
placed on the top of this beaker and then the entire assembly was placed
into a freezer for FMVC processing at 9.5 inches of vacuum. The samples
were removed from this solution after five hours of treatment and each was
lightly wiped with paper towel to remove free flowing siloxane. The
samples were then placed into one pint sized containment chambers, which
were fashioned by inverting a polyethylene container with a tight fitting
lid such that the lid of the unit acted as a flat base. Twenty grams of
dibutyltindiacetate (DBTDA) were placed in the catalyst tray and then both
samples were placed on a paper towel covered screen over the catalyst
tray. The containment chamber was then placed in position over the samples
and tightly closed. The entire assembly was then placed into a vented
warming oven that had been set at 160.degree. F., for 18 hours of vapor
deposition. One of these samples was tested and it was designated sample
"A". Three additional samples were treated in essentially the same way.
These samples were designated "B", "C", and "D". Samples "E" and "F" were
treated differently as can be found in TABLE IV below.
TABLE IV
__________________________________________________________________________
SAMPLE
SILOXANE
CROSSLINKER
CATALYST
OBSERVATIONS
MICROSCOPY
__________________________________________________________________________
A Siloxane 6
mtm dbtda Dry, slightly
Siloxane
stiff, white
throughout
stress
marks
B Siloxane 5
mtm dbtda
dry, supple
"
white stress
marks
C Siloxane 4
mtm dbtda
more supple
"
than 2, slightly
damp
D Siloxane 2
mtm dbtda
supple but
"
damp
E* " " " not as opaque
"**
as A-D
F
Fresh hide, no treatment
not as opaque
"
control sample
as A-D
__________________________________________________________________________
*Fresh hide, 6 hours of FMVC
**more opaque than D
EXAMPLE 5
A bobcat pelt, consisting of the entire head and back pelt from the animal
was acetone dehydrated at ambient pressure and room temperature and then
preserved using a curable siloxane as in example 4. The pelt was
successfully preserved.
EXAMPLE 6
Chromium-blue partially processed bluestock cowhides and finished buffed
hides, were treated as in Example 4. After treatment using
dibutyltindiacetate as the catalyst, all of the samples were
thin-sectioned for microscopic analysis. In all cases, the sections of
bluestock had been thoroughly impregnated with the curable siloxane
systems.
EXAMPLE 7
A piece of tanned and buffed cow hide was successfully impregnated with a
curable siloxane system using the siloxane polymer of example 4 and using
about three weight percent phenylmethyldimethoxysilane as a curing agent.
The leather was lightly wiped with paper towel and then treated with
dibutyltindiacetate in a small containment chamber.
EXAMPLE 8
A similar piece of leather was treated with a curable siloxane system which
consisted of the siloxane of Example 13 catalyzed with 3% DBTDA.
EXAMPLE 9
A dog heart used in this experiment was about the size of a large chicken's
egg in volume. After soaking the heart in cold running water for one hour,
the heart was gently massaged for approximately five minutes while
submerged in cold water to facilitate the removal of as much blood from
the organ prior to treatment. After allowing the heart to drip dry of free
flowing water for a few minutes, the heart was placed into 2 liters of
fresh acetone and allowed to passively dehydrate in a covered container at
room temperature for two days. The heart was then placed into a fresh bath
of acetone and placed into a freezer for FMVC water/acetone displacement
for 8 hours at 9 inches of vacuum.
The heart was then removed from the acetone bath and placed into a solution
of siloxane 3 into which had been added 3 weight percent of MTM. The
process of acetone/siloxane displacement was started at room temperature
for a period of 2 hours, in a large vacuum chamber with a recorded vacuum
of 28 inches. The organ in solution was then placed into a freezer mounted
vacuum chamber for 18 hours of continuous processing at 9.5 inches of
vacuum. The heart was left in solution at ambient pressure in the freezer
for 16 hours and then acetone/siloxane displacement was continued for an
additional 6 hours at 9.5 inches of vacuum. The heart was then removed
from the freezer and allowed to stand at room temperature in the solution
for 2 hours. The heart was then transferred into another container and
submerged in a solution of siloxane (1) from example 13 which contained 3%
MTM. The heart was then returned to the freezer for 4 hours of FMVC
treatment at 9.5 inches. After the acetone/siloxane displacement process
was completed, the heart was removed from the silicone oil and placed on a
mesh screen, suspended over another large beaker. In this position,
excess, free flowing siloxane was allowed to drip from the surfaces of the
heart for one half hour. The heart was then surface wiped to remove areas
of heavily pooled siloxane from its surfaces. Using a small eye dropper,
four drops of DBTDA were inserted into the uppermost large open end of an
artery, located at the top of the heart.
The heart was then placed into a large containment chamber, fashioned by
placing a large polyethylene pail and its tight fitting lid in an inverted
position. In this position, the lid of the unit acted as a flat base on
which a catalyst tray and specimen could be placed. Centrally located on
the base of the containment chamber, a flat tray containing three ounces
of DBTDA was held in position using a small piece of double sided tape. A
large piece of mesh screen was placed on top of this catalyst tray and its
edges were folded over to firmly attach the screen to the sides of the
catalyst tray. This screen acted as a platform on which the heart could be
placed allowing it to be positioned directly over the fumes of catalyst
during treatment. With body of the containment chamber placed in position
and firmly sealed, the assembly was then placed in a vented warming oven
set at 160.degree. F. The catalyst treatment lasted for 24 hours and then
the heart was removed form the oven, placed into a vented fume hood and
left in it containment chamber for five days at room temperature. Total
time for the conservation process was seven days, although it is believed
that the process should not take more than 4 to 5 days at the most, under
normal non-experimenting conditions.
After the treatment, the heart was cut in half using a long blade knife.
Thin sections of tissue taken from the thickest areas of the wall of the
heart were collected and microscopic analysis of the samples indicated
that the deep tissues of the heart had been successfully impregnated and
crosslinked with the siloxane. Aesthetically, the heart is very natural
looking. Contrary to prior art methods used for preserving heart tissue,
i.e. the Von Hagens process, the veins and arteries do not need to be
especially dye colored since the inventive process appears to maintain the
red coloration of blood within the vessels of the tissue.
EXAMPLE 10
Several pig hearts were placed in a large container of fresh, cold water
which was connected to the container such that fresh water was pumped
through the container continually. Additionally, the water was aerated
such that it aided in the cleansing and removal of much of the blood
remaining in the hearts. Aerated soaking continued for twenty four hours
at room temperature. After cleaning, six of the hearts were stored in a
water bath in a freezer. The remaining two hearts labelled samples 1 and 2
were FMVC treated in fresh acetone for 48 hours at 9.0 inches of vacuum.
After this step, the hearts were removed from FMVC treatment and placed
into a fresh bath of acetone. Passive dehydration continued for an
additional 48 hours at room temperature. Sample 1 was removed from acetone
and placed into a 4 liter stainless steel beaker containing 2 liter of
siloxane 2, which had 3% MTM added to it. The assembly of the equipment
was similar to that found in Example 16. A vacuum plate was placed over
the top of the stainless steel beaker and after securing, the entire
assembly was placed into a freezer for 58 hours of FMVC processing at 9.5
inches. The heart was left in solution sitting in the freezer at ambient
pressure for 5 hours.
Sample 1 was then removed from the FMVC assembly and placed on a section of
screen, sitting over a large container. In this position, the heart was
allowed to drain of the free flowing siloxane for a short period of time
and then the surfaces of the heart were wiped lightly with paper towel.
Sample 1 was then placed into a large beaker containing 500 ml. of fresh
MTM and moved around in the solution for approximately one minute. After
this step, the heart was removed from the MTM and allowed to sit on paper
towel until the containment chamber was prepared. At this time, the sample
was wiped with paper towel that had been moistened with a few drops of
DBTDA. Care was taken to ensure that all exterior surface of the heart had
been wiped with the catalyst.
The containment chamber was set up as in the previous example. Thirty grams
of DBTDA was placed in the catalyst tray. The containment chamber was then
placed in a vented warming oven that had been set to 160.degree. F. After
24 hours of vapor deposition, the sample was removed from the oven and
thin sections cut from the thickest parts of the heart showing that these
thick parts of the heart were not firm and had not been totally treated by
the process. Fresh catalyst was added to the catalyst tray and this sample
was returned to the chamber. The unit was returned to the oven for an
additional 48 hours of catalyst vapor deposition. The sample was removed
from the oven and again, thin sections were taken for analysis. On
evaluation, it was noted that there was an even distribution of cured
silicone throughout the tissues of the heart. The heart appeared
aesthetically nice and did not have any characteristic odor of
decomposition.
Sample 2 was allowed to passively dehydrate for 168 hours in acetone at
room temperature. It was then treated with water/acetone displacement for
6 hours using FMVC processing at 15 inches vacuum. The sample was then
removed from the FMVC assembly and placed into a 4 liter stainless steel
beaker containing siloxane 2 and 3% MTM and 0.1 weight % of DBTDA. The
sample was then subjected to the FMVC process for 19.5 hours. The sample
was then removed and drained of the siloxane fluid. It was then dipped
into fresh MTM for two minutes and moved about in the MTM. It was allowed
to drain and then placed into the containment chamber and 3 ounces of
DBTDA placed in the catalyst tray. The entire assembly was then placed
into the oven at 160.degree. F.
It was left there for approximately eight days to ensure the deep section
cure. Under microscopic evaluation, it was evident that the deep tissues
of the heart had been successfully impregnated and cured. There was no
odor of degradation.
A third pig heart was initially placed into a 4 liter stainless steel
container and placed into FMVC water/acetone displacement for 48 hours
passive treatment. The heart then received an additional 16.5 hours of
FMVC treatment at 2.0 inches of pressure. The heart was then removed from
the freezer and placed into 2 liters of fresh acetone where it was allowed
to continue passive dehydration in room temperature acetone for 48 hours.
The acetone was replaced daily so that through the two day period of
dehydration at room temperature, the acetone was changed once.
This heart, sample 3, was then removed from the water/acetone displacement
and placed directly into a stainless steel beaker containing 2 liters of
siloxane 2 with 3 weight % MTM added thereto. The heart was weighted down
with a section of mesh screen and a small weight and a vacuum plate was
attached to the top of the beaker and the entire assembly was placed into
a freezer for FMVC acetone/siloxane displacement at 2.0 inches of vacuum.
The heart remained in treatment for 9 hours at 9.0 inches of vacuum.
The heart was then removed from the siloxane and placed on a section of
mesh so that free flowing siloxane could drip from the surface. The
surface was wiped gently with a paper towel. DBTDA was then applied to the
surface by hand, using a cotton glove covering a rubber glove and the
heart was massaged to cover all of the crevices and irregularities of the
surface. In addition, DBTDA was placed in the catalyst try and the heart
was treated by sealing the chamber and warming the oven for 6 days at
160.degree. F.
Upon removal from the oven, the heart had a firm texture and microscopic
analysis of several thin sections indicated that the heart was completely
preserved.
EXAMPLE 11
A pig heart, designated "B" was dehydrated in acetone for 48 hours in the
freezer mounted vacuum chamber. This was followed by two days of passive
acetone dehydration at ambient pressure and room temperature. Fresh
acetone was then placed in the stainless steel container and the heart
remained in passive dehydration for an additional 168 hours and then the
organ was further dehydrated in acetone using freezer vacuum for an
additional six hours. It was then treated with a curable system using the
system set forth in example 4. The heart was drained of free-flowing
solution, placed in methyltrimethoxysilane for two minutes and then
treated with dibutyltindiacetate in a conventional containment chamber
set-up. It was treated for eight days. Microscopic investigation showed
that the heart had been thoroughly conserved by the cured siloxane system.
EXAMPLE 12
A third pig heart, designated "C" was treated with extensive acetone
dehydration prior to conservation. Then the heart was treated to 48 hours
of freezer mounted vacuum chamber dehydration followed by two days of
sitting in acetone in the freezer at ambient pressure. The heart was then
placed in fresh acetone and allowed to sit at ambient pressure and room
temperature for an additional two days. After treating with a curable
siloxane system as in example 4, for thirty three hours, the heart was
removed from the solution and the surface wiped with paper towel.
Dibutyltindiacetate was then massaged into the surfaces and crevices of
the heart. After six days of this treatment, the heart was completely
conserved.
EXAMPLE 13
Preservation of Old Paper
Pages of a very old book which were yellowed and brittle were crumpled by
hand and then placed into a common blender and reduced to a fine
consistent powder.
Six samples were prepared, each containing 7.0 gms. of Siloxane 2 and 1.25
gms. of the crumpled paper. These samples were labeled 1A, 1B, 1C, 1D, 1E,
and 1F. Eight additional samples, each containing 7.0 gms. of the siloxane
fluid and 3 weight % methyltrimethoxysilane and 1.25 gms. of paper were
mixed in individual aluminum trays. These were labeled as 2A, 2B, 2C, 2D,
2E, 2F, and 3B, and 3D.
Identical containment chambers, like those used in previous experiments
illustrated above, were used for this experiment. Thus, individual
containment chambers were created for this experiment using one pint
polyethylene cups with tight fitting lids. In an inverted position, the
lid formed a flat base with the body of the container acting as a lid. Two
one quart jars were used as containment chambers for samples 3B and 3D.
Placement of catalyst and sample trays was done exactly the same as in the
previous examples. Other than material composition, the volume with the
glass chambers was double that of the polyethylene cups. A small piece of
double sided tape was used to secure an aluminum sample tray to the base
of the unit. In this tray, the designated catalyst for the sample being
tested was placed. A piece of open mesh screen, measuring approximately
1.75 inches square was then placed over the aluminum tray and its edges
were folded over to secure the screen on top of the catalyst tray. This
screen acted as a mounting platform upon which an aluminum tray holding
the sample being tested was placed. In this position, the sample was
directly above the catalyst tray, minimizing any splashing that might
occur while placing the containment chamber in the warming oven. With the
body of the containment chamber in place, all samples were then placed
into a vented warming oven which had been set at 70.degree. C. Vapor
deposition continued in this oven for 48 hours. The results are listed
below in TABLE V.
TABLE V
______________________________________
CHAMBER
SAMPLE TREATMENT
CATALYST
TYPE RESULTS
______________________________________
1A Siloxane 2 Sn(Oct).sub.2
Op 1
1B " 1 C
1C " 2
1D " " C 2+
1E " Op TPT
1
1F " C 1"
2A Siloxane 2 + MTM
Sn(Oct).sub.2
Op
2
2B " " 4+ C
2C " 3
2D " 5
2E " Op TPT
4+
2F " C "
5
3B " G/C 2+b.2
3D " G/C DBTDA
2+
______________________________________
TABLE V KEY
MTM = Methyltrimethoxysilane
DBTDA = dibutyltindiacetate
TPT = tetraisopropyltitanate
Op = open, where the top of the jar was left open inside of the
containment chamber.
C -closed, where the top of the jar was closed inside of the
containment chamber.
G/C = glass container, closed
0 = no change in the material.
1 = some thickening of the material
2 = very thick, some gellation
3 = very thick, light crosslinking, some crusting
4 = very nearly cured, slightly tacky
5 = totally cured, solid, nontacky
EXAMPLE 14
Conservation of Glass
Experiments using glass as the substrate were carried out using the same
methodologies as were used for the paper above.
Panes of glass were placed in a plastic bag and hammered until the glass
was reduced to very small particles. The particles were then placed into a
blender and by using the pulse button, the particles were reduced to a
very fine glass particle.
The ratio of glass to the treatment material was 15 grams of glass to 3.55
of the treatment material which consisted of the same materials in the
same ratios as was used in Example 13.
The results can be found in TABLE VI.
TABLE VI
______________________________________
CHAMBER
SAMPLE TREATMENT
CATALYST
TYPE RESULTS
______________________________________
1A Siloxane 2 Sn(Oct).sub.2
Op 1+
1B " 4+ C
1C " 1+
1D " " C 4+
1E " Op TPT
1+
1F " C 5"
2A Siloxane 2 + MTM
Sn(Oct).sub.2
Op
1+
2B " " 7 C
2C " 5+
2D " 7
2E " Op TPT
2
2F " C "
5
3B " G/C 6+b.2
3D " G/C DBTDA
5+
3F " TPT G/C 6
______________________________________
MTM = Methyltrimethoxysilane
DBTDA = dibutyltindiacetate
TPT = tetraisopropyltitanate
Op = open, where the top of the jar was left open inside of the
containment chamber.
C closed, where the top of the jar was closed inside of th
containment chamber.
G/C = glass container, closed
0 = no change in the material.
1 = some thickening of the material
2 = very thick, some gellation
3 = very thick, light crosslinking, some crusting
4 = very nearly cured, slightly tacky
5 = totally cured, solid, nontacky
6 = very nearly cured, solid and tacky
7 = totally cured, solid and nontacky
EXAMPLE 15
Conservation of Onion Bottle Glass
This experiment was carried out on waterlogged, devitrified archaeological
glass which was recovered from excavations of the 1692 provenance of Port
Royal, Jamaica.
The glass was in fragments and these fragments were taken from a section of
broken bottle which are commonly called onion bottles. These bottles are
found in abundance at the Port Royal site. When recovered from excavations
at the site, care must be taken to keep these bottles wet during transport
to the lab and during curation in preparation for conservation. If allowed
to air dry, it is not uncommon to see large layers of flakes exfoliate
from the surfaces to the bottles, much like removing layers from an onion.
If left to dry, an intact bottle can be reduced to rubble in a short
period of time.
Before treatment with the siloxanes, all samples of glass were placed into
a large stainless steel beaker and immersed in one liter of fresh acetone.
The samples were then dehydrated in a freezer mounted vacuum chamber for
four hours at a high vacuum. The glass was then removed from the acetone
and placed into a 200 gram solution of siloxane 2, to which 3 weight
percent of methyltrimethoxysilane was added. The samples in solution were
then placed in a freezer and a vacuum plate was placed over the stainless
steel beaker. Acetone/silicone solution displacement was conducted on this
these samples for six hours under vacuum. After this treatment, the glass
samples were removed from the siloxane mixture and gently blotted with
paper towel to remove most of the free flowing and surface pooled liquid.
The samples were then subjected to catalyst vapors according to the
apparatus and procedures as set forth in Example 13. Thirteen gms. of
dibutyltindiacetate were placed in the catalyst tray for these experiments
and the containment chamber was heated to about 160.degree. F. and the
samples were left therein for about sixteen hours. TABLE VII lists the
treatments for samples 1 through 3.
TABLE VII
______________________________________
SAMPLE TREATMENT CATALYST
______________________________________
1 siloxane 2 + 3% MTM
DBTDA
2 siloxane 5 + 3% MTM
"
3 siloxane 4 + 3% MTM
"
______________________________________
Several additional samples of glass were prepared. The process for sample 4
was modified in that after acetone dehydration, the sample was removed
from acetone and placed directly into a container of MTM with a sufficient
amount to submerge the glass sample totally. The sample in solution was
then placed into a large stainless steel beaker and after placing a vacuum
plate over the beaker, a vacuum was applied for six hours. After this
treatment, the glass was lightly surface blotted with paper towel. After
blotting, the sample was placed into an individual containment chamber
identical to the type described above. The sample was then placed along
side the other samples in the vented warming oven for 16 hours at
160.degree. F.
Sample 5 was not acetone dehydrated prior to treatment. The sample was
rinsed in fresh running water and then submerged in a beaker of fresh MTM.
The beaker containing the sample in solution was placed into a four liter
stainless steel beaker and after a vacuum was applied, the entire assembly
was placed inside a freezer for six hours.
After this treatment, the sample was left in the freezer in solution and at
ambient pressure for approximately 18 hours and then subjected to the
catalyst vapor for twenty-four hours at 160 degrees F.
Sample 6 consisted of four small samples of glass. These samples were
rinsed in running tap water for approximately one hour and then placed
directly into 200 grams of siloxane 3 from above in which there was
present 30 MTM. These samples were then placed in a freezer mounted vacuum
chamber and treated in solution for six hours under vacuum.
After this treatment, the samples were left in solution in the freezer at
ambient pressure for approximately eighteen hours. The samples were
removed from the siloxane mixture and lightly patted with paper towel to
remove free flowing surface solution. The samples were then placed into
the same configuration of containment chamber was used in the previous
Examples. The samples were subjected to catalyst vapor as above, for 24
hours at 160.degree. F.
The samples were subjectively evaluated for clarity of glass, overall
aesthetics, presence or absence of a "rainbow" discoloration or filminess
on the surface of the glass and overall integrity of the samples. The
results can be found on TABLE VIII.
TABLE VIII
______________________________________
SAM-
PLE INITIAL EVALUATION
24 HOUR EVALUATION
______________________________________
1
slightly tacky, glossy, to
Good overall
semi-glossy, no flaking,
aesthetically good
2 dry, glossy to semi-gIossy,
Very good overall
good color, oxides on glass
are consolidated
3 surface not uniformly coated,
Reasonably good
some pooled and cured siloxane,
not aesthetically pretty
4 dry, clear, aesthetically good
to Excellent
overall
5 rainbow coloration, opaque layer
Very poor
noted, dead glass appearance, poor
6 slight rainbow coloration, glass
Reasonable
not flaking, surface appears stable
appearance
7 uniform glass color, material is
Good to
well consolidated
Excellent
______________________________________
EXPERIMENT 16
Preservation of Fish
Sample experiments were carried out to try to preserve fish using small
goldfish. It appeared that the use of vacuum during the processing did not
lend itself well to the preservation of the goldfish because it was
observed that the fish were too fragile for the vacuum treatment and
essentially split and otherwise came apart.
Therefore, the procedure was modified. Two goldfish specimens were
subjected to long term passive dehydration. These fish were stored in
fresh acetone for two months at room temperature and ambient pressure.
After dehydration, the specimens were placed into the siloxane 3
containing MTM. The fish were weighted down so that the solution covered
them. They were treated in this manner for 2 hours at room temperature.
Then vacuum was increased slowly over the first thirty minutes of
treatment, ultimately reaching a vacuum of 28 inches. The samples were
then transferred to a freezer for 1 hour of FMVC treatment. The samples
were left in solution in the freezer at ambient pressure over the weekend.
The samples were retreated using the FMVC process for an additional 7.5
hours at 2 inches of vapor pressure. The samples were then removed from
the freezer and solution and lightly patted on the surface with paper
towel. Sample 1 was then placed into a small containment chamber using the
same methodologies as was used for the Example 13 samples. With 20 grams.
of DBTDA in the catalyst tray, the sample was sealed in the container and
then the sample was placed into a vented warming oven set at 160 degrees
F. for 18 hours.
Sample 2 was removed from the siloxane mixture and after lightly patting
the surface with a towel, the sample was mounted onto a small containment
chamber. Twenty grams of tin dioctoate were used for the catalyst. This
treatment was carried out for 18 hours. After this treatment, both samples
were removed from the oven and allowed to sit for 24 hours.
Sample 1 was totally dry and aesthetically pleasing. The skin texture of
the fish and the fine details of the fins were all well preserved. Sample
2 was equally well preserved although there was a slight blemish or
blotchy appearance on one side of the finished specimen. The samples were
both very natural looking and appeared to be well preserved.
EXAMPLE 17
This is an example of a silane crosslinker having both alkoxy and acyloxy
substituents on the silicon atom to give mixed groups on the silicon atom.
The silane crosslinker was prepared by adding in 25 gm increments, reagent
grade isopropanol to 225 gms of Methyltriacetoxysilane which had been
placed in an open top pint glass jar. The addition of the isopropanol
creates a slight exotherm, and the lower one third of the glass jar was
immersed in ice water to cool it. After the addition was complete, the jar
was capped and it was allowed to stand several hours to complete the
formation of the mixed crosslinker.
A sample 1 was prepared. It consisted of a corn cob which had been
excavated from the Yorktown ship wreck which was subjected to the process
described herein. Thus, the corn cob was subjected to room temperature
vacuum in a vacuum chamber while sitting in fresh acetone for 7 hours, at
which point, the rapid bubbling observed from the sample diminished to
nothing. The corn cob was then placed into a hydroxy functional linear
polydimethyl silicone polymer having about 100 dimethyl units which
contained about 7 weight percent of the crosslinker prepared just above.
A screen was placed on top of the object to prevent floating in the acetone
and subsequently in the immersion in the silicone solution. The sample and
the solution was then subjected to vacuum in a vacuum chamber for 7.5
hours at a maximum vacuum of 4 mm. The sample was removed at that time and
placed onto aluminum screen and allowed to drip free of free-flowing
silicone solution and the sample was then placed in a fume hood and
allowed to auto-catalyze. Note that no catalyst was added to this
procedure.
A second sample was treated as above, but at the end of the drip free step
of the process, the sample was patted dry with paper towels, and then with
a lint free cloth. The sample was then coated with dibutyltindiacetate
topically applied with Q-tips to all exposed surfaces. Excess silicone
solution, if any, and excess DBTDA was lightly blotted after letting the
sample sit for approximately 5 minutes in the open air.
The sample 1 after curing at room temperature for about 12 hours, did not
shown any significant shrinkage. It was slightly tacky to the touch with a
small amount of distortion noted around the middle girth. It had a small
amount of rippling to the surface but otherwise had a natural corn cob
look to it.
Sample 2 had broken approximately in half during the process. There was no
significant distortion and the sample was dry to the touch after 12 hours
of cure at room temperature in ambient air. Sample was heavily coated as
compared to sample 1 as no effort had been made to blot the sample before
treating with the DBTDA because of the rapid polymerization or
crosslinking of the silicone materials. The sample did not have any
surface rippling and appeared natural. Also, this sample is more firm than
sample 1.
EXAMPLE 18
An additional mixed crosslinker was prepared by adding 100 gms of octanoic
acid to 100 gms of methytriacetoxysilane and 0.4 gms of DBTDA. This
solution was allowed to sit one week in a closed jar before using.
Sample 1 consisted of a corn cob with the archival number AS195. This corn
cob was very fragile. A second sample which had been identified as AS241,
i.e. the "long cob" were both placed in acetone and a vacuum was pulled
for 3.5 hours, that is until no bubbles could be seen emanating from the
solution. Both cobs remained in the vacuum chamber overnight (12 hours)
without additional vacuum being applied.
The first sample, which had broken into smaller pieces, was immersed in a
mixture of 168 gms of hydroxyl end-blocked polydimethylsiloxane having a
degree of polymerization of about 100 and 14 gms of the cross-linker
prepared just above. The mixture thickened quickly.
The second sample was placed in a solution of 279 gms of the siloxane
polymer and 21 gms of the crosslinker, the additional amount of solution
being needed to totally immerse the long section of corn cob.
Both samples were held into the solution by several wire-mesh restraints. A
vacuum was drawn and the sample began to evolve bubbles. The vacuum was
shut off and the vacuum released. The samples were removed from the
solution and were already polymerizing such that the samples could not be
blotted. The samples cured after a short time. There was little or no
distortion to either of the samples and neither of the samples had shrunk.
The coloration was good and the surfaces were heavily coated because of
the fast polymerization.
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